From: Gao Xiang <hsiang...@redhat.com> Hi folks,
When we provides support for different algorithms or big pcluster, it'd be necessary to record some configuration in the per-fs basis. For example, when big pcluster feature for lz4 is enabled, we need to know the largest pclustersize in the whole fs instance to adjust per-CPU buffers in advance, which will be used to handle in-place decompression failure for inplace IO then. And we also need to record global arguments (e.g. dict_size) for the upcoming LZMA algorithm support. Therefore, this patchset introduces a new INCOMPAT feature called COMPR_CFGS, which provides an available algorithm bitmap in the sb and a variable array list to store corresponding arguments for each available algorithms. Since such a INCOMPAT sb feature will be introduced, it'd be better to reuse such bit for BIGPCLUSTER feature as well since BIGPCLUSTER feature depends on COMPR_CFGS and will be released together with COMPR_CFGS. If COMPR_CFGS is disabled, the field of available algorithm bitmap would become a lz4_max_distance (which is now reserved as 0), and max_distance can be safely ignored for old kernels since 64k lz4 dictionary is always enough even new images could reduce the sliding window. Thanks, Gao Xiang Gao Xiang (3): erofs: introduce erofs_sb_has_xxx() helpers erofs: introduce on-disk lz4 fs configurations erofs: add on-disk compression configurations Huang Jianan (1): erofs: support adjust lz4 history window size fs/erofs/decompressor.c | 35 ++++++++-- fs/erofs/erofs_fs.h | 23 +++++-- fs/erofs/internal.h | 33 +++++++++ fs/erofs/super.c | 149 +++++++++++++++++++++++++++++++++++++++- 4 files changed, 228 insertions(+), 12 deletions(-) -- 2.20.1
